The present invention relates in general to Raman identification of particles and in particular, to fluorescence-cued Raman identification of viable organisms.
Standard microbiological methods developed to determine whether bacterial cells are dead or alive generally rely upon the ability of the tested bacterial cells to grow and produce colonies as a measure of the viability of the bacterial cells under test. However, industries such as the pharmaceutical industry are concerned about the identification of viable particles including organisms that are viable, but non-culturable. For example, certain bacteria may go into a viable but non-culturable state wherein the bacterial organisms have metabolic processes but are not undergoing cell division. In this state, bacteria are still viable, but may not be shown as colony forming units under nonselective growth conditions using common techniques such as conventional plate counts. Such viable but non-culturable bacteria may comprise a concern, for example, in public health risk assessments because certain pathogenic bacteria may be able to transition between a viable but non-culturable state and an infectious state.